The plasma alarm clock

By the time you read this, winter will be heading toward
its end, either by crawling along slowly or by happily retreating so that the
sun can finally make its triumphant return. That means it is almost time for
another planting season – but for now, we are still often constrained by
waiting for the seasons to change.

One group of scientists is currently working on a project
that might give us humans an advantage over waiting for Mother Nature to make
her move. Let’s look at plasmas – the “fourth state of matter,” the hot,
ionized gases can also be found
in lightning strikes, the hearts of stars and old neon signs.

In Saudi Arabia, a team of scientists at Jazan University
are using space-age technology to induce the sprouting of “sleeping”
grapevines. This could mean a way to extend the cultivation of crops that
normally only thrive in temperate zones to warmer regions of the planet. Crops like grapes, peaches, berries
and flower bulbs all go dormant during the winter, sleeping through the
seasonal cold before they resume growing, flowering and fruiting again. In
milder climates, plants often do not receive enough chilling time. Growth time
is unsynchronized, with some plants budding weeks before others, and this can
make it costlier for growers to provide proper care – especially when it comes
to pest control, labor costs and lower yields. The scientists are using plasmas
to “wake up” the grapevines that are sleeping longer than their peers.

The work of
horticulturist Habib Khemira, plasma physicist Zaka-ul-Islam Mujahid and plant
physiologist Taieb Tounekti may help to extend the cultivation of fruit crops
and ornamental plants native to temperate climates to parts of the world where
winters are milder, including the southern half of the U.S. It may also
mitigate the problems posed by rising temperatures due to climate change. “Artificial
methods to release dormancy are expected to become more important in the near
future due to global warming,” said Mujahid.

Plants
sense the cold of winter and keep track of freezing days. When enough of those
cold days occur, the plants respond by increasing their metabolic processes which
leads to bud break and shoot growth when the warmer days of spring arrive. When
plants grow in regions with milder winters, however, they may not receive
enough chilling to release their buds on time. One of the biggest challenges of
modern farming is finding ways to push the maximum number of buds on plants to
grow, to flower and to bear fruit all at the same time.

Plasma
exposure causes an oxidative stress within the plant, the exact same signal from
cold in the cells of dormant plants to which the buds respond by awakening. In
treating grape buds with plasmas, the researchers discovered they could release
the plant’s dormancy – much quicker than the weather can and more safely than spraying
the crops with chemicals to induce the same reaction.

“Some of
the results from our first successful experiment were phenomenal, and we could
not believe it was true,” Mujahid said. Just a few minutes of plasma treatment
on buds that never saw cold weather allowed the plants to achieve similar, if
not better, bud break as control plants that experienced optimal cold
conditions (60 days of exposure to temperatures about 40 degrees Fahrenheit)
did. Note that although the method worked well in the laboratory, it still
needs to be field tested.

Whether
the plasma approach to treating dormant buds takes off depends on several
things, including whether it would work effectively in the field as well as it
did in the laboratory. It needs to be tested on crops other than grapes, and
the cost of the equipment also needs to be taken into consideration.

“There is
still a lot of work to test the effectiveness and feasibility,” Mujahid said. “We
are in the process of figuring out the proper parameters to take it to the
field but it could be in use within just a few years.”